In wireless telecommunication networks, such as cellular wireless networks, a radio access network (RAN) may transmit messages to mobile devices that are in an idle state, i.e., mobile devices that are not engaged in any communication sessions. Such messages may include, for example, overhead messages that convey configuration parameters or system-related information, and page messages that direct specific mobile devices to contact the RAN (e.g., in relation to incoming calls).
In order to save power, a mobile device in an idle state may operate primarily in a low-power, sleep mode. In sleep mode, the mobile device's transceiver may be powered down so that the mobile device does not receive transmissions from the RAN. However, at certain times, the mobile device may “wake up” from the sleep mode and monitor a designated channel for transmissions from the RAN. For example, a mobile device may operate in a slotted mode in which the mobile device wakes up periodically (e.g., during specified time slots) to monitor transmissions from the RAN in a paging channel or control channel.
How frequently a mobile device wakes up from sleep mode to monitor transmissions from the RAN may depend on the type of communication sessions that the mobile device supports. For communication sessions that are highly sensitive to latency, such as push-to-talk (PTT) communication sessions, a mobile device may wake up from sleep mode very frequently. For communication sessions that are less sensitive to latency, such as conventional voice calls, a mobile device may wake up less frequently.
A recent standard for Evolution Data-Optimized (EVDO) spread spectrum communications, 3rd Generation Partnership Project, “cdma2000 High Rate Packet Data Air Interface Specification,” 3GPP2 C.S0024-B, September 2009, describes a “Sleep State,” in which a mobile device may shut down processing resources to reduce power consumption, and a “Monitor State,” in which a mobile device monitors a control channel to receive overhead messages and to listen for page messages.
To listen for page messages while in the Monitor State, the mobile device may receive a synchronous sleep state capsule that the RAN transmits on the control channel. Each synchronous sleep state capsule includes a QuickConfig message (an overhead message) and zero or more page messages. When a mobile device receives a synchronous sleep state capsule, the mobile device receives the QuickConfig message and any page messages contained in the capsule. The page messages may include one or more page messages intended for that mobile device and/or one or more page messages intended for other mobile devices. Once the mobile device has received the entire synchronous sleep state capsule (the last packet in the synchronous sleep state capsule is marked with a SleepStateCapsuleDone flag), the mobile device may return to the Sleep State.